/*-
 * Copyright 2012 Guram Dukashvili
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
//---------------------------------------------------------------------------
#ifndef __rwlock_h__
#define __rwlock_h__
//---------------------------------------------------------------------------
#include "config.h"
#include "mutex.h"
//---------------------------------------------------------------------------
#if HAVE_PTHREAD_H
#include <pthread.h>
#endif
#if HAVE_SEMAPHORE_H
#include <semaphore.h>
#endif
//---------------------------------------------------------------------------
#ifdef __cplusplus
extern "C" {
#endif
//---------------------------------------------------------------------------
enum RWLOCK_TYPE {
  RWL_NONE,
  RWL_UPGRADE,
  RWL_DOWNGRADE,
  RWL_READ,
  RWL_WRITE
};
//---------------------------------------------------------------------------
struct rwlock {
  struct semaphore lock;
  struct semaphore write;
  uint32_t readers;
  uint32_t write_waiters;
  uintptr_t writer;
};
//---------------------------------------------------------------------------
struct rwlock * rwlock_new(void);
void rwlock_init(struct rwlock * rwl);
void rwlock_destroy(struct rwlock * rwl);
void rwlock_delete(struct rwlock * rwl);
void rwlock_acquire_read_lock(struct rwlock * rwl);
bool rwlock_try_acquire_read_lock(struct rwlock * rwl);
void rwlock_acquire_write_lock(struct rwlock * rwl);
bool rwlock_try_acquire_write_lock(struct rwlock * rwl);
void rwlock_upgrade(struct rwlock * rwl); // lock escalation
void rwlock_downgrade(struct rwlock * rwl);
bool rwlock_try_upgrade(struct rwlock * rwl);
void rwlock_release_read_lock(struct rwlock * rwl);
void rwlock_release_write_lock(struct rwlock * rwl);
void rwlock_acquire(struct rwlock * rwl,enum RWLOCK_TYPE lock_type);
void rwlock_release(struct rwlock * rwl,enum RWLOCK_TYPE lock_type);
//---------------------------------------------------------------------------
#ifdef __cplusplus
}
#endif
//---------------------------------------------------------------------------
#endif
//---------------------------------------------------------------------------
